in my opinion, JR is not crucial in a PF, but for outside tactics, it sure helps to have a PF who can knock down 3s (think Kevin Love or Dirk Nowitzki).
If you have enough other trainees, raise his JS, Driving and Rebounding this season. IS should increase a little that way, via secondary training.
I'd worry a little about his OD, though. He'll be absolutely abused by outside PFs with a good jumper and some range. perhaps not this season, but next season I'd try to get it at least to mediocre, and rather even strong, or else you'll lose against every opposing team that plays either Princeton or Motion.